Jisho.org Forum

This is the home page:

http://www.e-pisco.jp/index.html

E-pisco seems to be an organisation that do research into predicting earthquakes. Which they say in Japanese on their home page, as well as having 'Precursory quake-Information System by Citizen's Observation' (PISCO) on the page you link to. When I googled "e-pisco" and "japan" I found this page with some information in English:

http://www.unisdr.org/wcdr/public-forum/poster-session.htm (right near the bottom of the page)

I'm not sure how you find the exact date the page you link to was written, but at the bottom of their home page they have 'Copyright 2004-2008'

I hope that helps you a bit.

Ok thanks, I probably hadn't thought about searching on google >.<<br />
But what does the title of the document mean: 震度階級: 気象庁震度階級（明治17年～昭和23年）

Meiji 17 to Showa 23, I guess, which years are that in the gregorian(our?) calender?

Litteral translation of what you posted:

Grades of the Japanese earthquake scale: Grades of the meteorological agency's Japanese earthquake scale (1884-1948)

The document explains how the grades in the japanese earthquake grade changed over those years.

Okey, thanks! ^^

For the year conversion, here are a couple of links.

japan-guide.com has a calculator, similar to a currency converter, for Gregorian-Japanese and vice versa from 1868-2008:
http://www.japan-guide.com/e/e2272.html

hanga has a date conversion chart, which I think looks better visually (I prefer to have an overview of all the data in front of me, not just one year), but only covers 1900-2001:
http://www.hanga.com/exhibit.cfm?ID=5